1. Field of the Invention
This invention relates to a lawn mower having front wheels, a pair of right and left rear drive wheels, a body frame, a mower unit supported by the body frame forwardly of the rear drive wheels, a grass catcher attached to the rear of the body frame, an engine mounted on the body frame, a left change speed device for changing speed of drive from the engine, and transmitting it to a left axle of the left rear wheel, a right change speed device for changing speed of drive from the engine, and transmitting it to a right axle of the right rear wheel, and a grass collecting duct connected at one end thereof to the mower unit and the other end to the grass catcher.
2. Description of the Related Art
It is the most desirable to pass the grass collecting duct through a space between the rear wheels. Since the rear axles are obstructive, the above-noted lawn mower has the grass collecting duct extending through a laterally outward area of the vehicle body. However, the grass collecting duct protruding laterally of the vehicle body increases the width of the vehicle body, and impairs operability of the vehicle body. To eliminate these drawbacks, as disclosed in Japanese Patent Publication (Unexamined) 2001-45826 (corresponding to U.S. Pat. No. 6,360,517 B1), for example, a proposal has been made to arrange a change speed device including an HST (hydrostatic stepless transmission) and gear type change speed mechanisms, and a grass collecting duct, in a space produced by lowering the rear axles.
However, according to the above prior art, the vehicle body has a bad right and left balance since the heavy change speed device and light grass collecting duct are juxtaposed right and left in the space formed in a transversely middle region of the vehicle body. Further, the grass collecting duct disposed to one side results in an inconvenience of grass clippings accumulating in the side of the grass catcher connected to the grass collecting duct.
Moreover, the lowered rear axles have a reduced height over the ground. This increases the possibility of the rear axles colliding with obstacles on the ground, and renders the lawn mower unsuitable for running over a rough ground.
The object of this invention is to provide a lawn mower having a grass collecting duct extending through a space between rear wheels to realize improved right and left balance of a vehicle body and sideways compactness of the vehicle body, with rear axles having a sufficient height over the ground.
The above object is fulfilled, according to this invention, by a lawn mower comprising, front wheels, a pair of right and left rear drive wheels, a body frame, a mower unit supported by the body frame forwardly of the rear drive wheels, a grass catcher attached to a rear end of the body frame, an engine mounted on the body frame, a left change speed device for changing speed of drive from the engine, and transmitting the drive to a left side of the left rear wheel, a right change speed device for changing speed of drive from the engine, and transmitting the drive to a right axle of the right rear wheel, and a grass collecting duct connected at one end thereof to the mower unit and at the other end to the grass catcher, wherein the left change speed device is disposed in a left region of the body frame to extend upward from the left axle, and the right change speed device is disposed in a right region of the body frame to extend upward from the left axle, the left change speed device and the right change speed device defining a space opening downward, the grass collecting duct extending through the space.
In this construction, the two change speed devices are arranged in the right and left side regions of the vehicle body, respectively, with the grass collecting duct extending through the space formed between the change speed devices. This arrangement improves the right and left balance of the vehicle body. Since drive is transmitted from the right and left change speed devices directly to the axles of the rear wheels, the axles have a sufficient height over the ground, with no axles interconnecting the right and left rear wheels.
Where drive from the engine is transmitted independently to the respective drive wheels through the right and left change speed devices, the right and left change speed devices may be shifted independently of each other to produce a straight running state in which the right and left drive wheels are driven at equal speed, a large turning state in which the right and left drive wheels are driven at different speeds in the same direction, a pivot turning state in which one of the right and left drive wheels is stopped, and a spin turning state in which the right and left drive wheels are driven in opposite directions. Each of these states may easily be selected according to working conditions.
In a preferred embodiment of this invention, each of the right and left change speed devices includes a stepless transmission such as an HST and a reduction mechanism such as a gear type change speed mechanism, the stepless transmission being disposed level with the rear wheel, the reduction mechanism extending vertically from the stepless transmission to the axle. The stepless transmissions that are structurally difficult to form into a thin configuration are arranged in an upper region. The reduction mechanisms that are easy to form into a thin configuration are arranged along side surfaces of the rear wheels. Thus, the space defined between the reduction mechanisms has an increased right and left width.
In a preferred embodiment for secure a satisfactory size of the above space, the body frame is formed of a pair of right and left band-like profile members extending fore and aft, the stepless transmissions being disposed above the band-like profile members, the reduction mechanisms being disposed outwardly of the band-like profile members.
In a further another embodiment, each reduction mechanism is fixed to an outer surface of the corresponding one of the band-like profile members. With this construction, all the area below the right and left band-like profile members may be used as the space for accommodating the grass collecting duct. For this purpose, it is important for the engine to be disposed level with or in a higher position than the stepless transmissions. Further, it is important that a drive distributing mechanism is disposed between and level with the right and left stepless transmissions for distributing drive from the engine to the right and left stepless transmissions.
To secure a good balance of the vehicle body, in a further embodiment, the grass collecting duct extends such that the center of a duct section substantially corresponds to the axles of said rear wheels.
Other features and advantages of this invention will be apparent from the following description of the embodiment to be taken with reference to the drawings.